Investigations of the structure, topology and interactions of the transmembrane domain of the lipid sorting protein p24 being highly selective for sphingomyelin-C18.
Fiche publication
Date publication
mai 2019
Journal
Biochemistry
Auteurs
Membres identifiés du Cancéropôle Est :
Pr BECHINGER Burkhard
Tous les auteurs :
Aisenbrey C, Kemayo-Koumkoua P, Salnikov ES, Glattard E, Bechinger B
Lien Pubmed
Résumé
The p24 proteins play an important role in the secretory pathway where they selectively connect various cargo to other proteins thereby being involved in the controlled assembly and disassembly of the coat protein complexes and lipid sorting. Recently, a highly selective lipid interaction motif has been identified within the p24 transmembrane domain (TMD) which recognizes the combination of sphingomyelin head group and the exact length of the C18 fatty acyl chain (SM-C18). Here we present investigations of the structure, dynamics and sphingomyelin interactions of the p24 transmembrane region using CD-, tryptophan fluorescence- and solid-state NMR spectroscopies of the polypeptides and the surrounding lipids. Membrane insertion and/or conformation of the TMD are strongly dependent on the membrane lipid composition where the transmembrane helical insertion is strongest in the presence of POPC and SM-C18. By analyzing solid-state NMR angular restraints from a large number of labelled sites a tilt angle of 19 degrees has been found for the transmembrane helical domain at a peptide-to-lipid ratio of 1 mole%. Only minor changes in the solid-state NMR spectra are observed due to the presence of SM-C18, the only visible alterations are associated with the SM-C18 recognition motif close to the carboxyterminal part of the hydrophobic transmembrane region in proximity of the SM head group. Finally, the deuterium order parameters of POPC-d31 are nearly unaffected by the presence of SM-C18 or the polypeptide alone, but decreases noticeably when the sphingomyelin and the polypeptide were added in combination.
Référence
Biochemistry. 2019 May 23;: